Lactase breaks down the excess lactose in the body into glucose and galactose. Glucose is the source of energy for the metabolism of various parts of the body, while galactose is a necessary tissue for the development of the infant brain and is closely associated with the rapid growth of the infant brain. Generally taking lactase for two or three days can see the effect, it mainly regulates the intestinal tract, such as the baby accumulation of food, indigestion. In the case of drinking granny regularly, it can be taken with warm water (30-40℃) 5-15 minutes before each feeding. An overdose of lactase in children can interfere with the normal physiological functions of the intestine, affecting the digestion and absorption of food, causing diarrhea, vomiting and other symptoms, and in serious cases, medical treatment is required. Lactase overdose will also increase the amount of glucose and lactose in the body, glucose will be turned into glycogen and stored in the body, glycogen will be converted into fat, so lactase overdose will also increase the amount of fat in the body. For diarrhea caused by lactase overdose, you can take probiotics to condition the intestinal flora balance or use montelukast to stop the diarrhea. It is important to note that when supplementing with lactase it is important to do so in moderation and never in excess. Parents should also pay attention to the issue of healthy and varied diet for their children.